KR20040040737A - Method and apparatus for inspecting semiconductor wafer - Google Patents

Abstract

Disclosed are a semiconductor wafer inspection method and apparatus using laser scattering. The apparatus scans each laser beam by irradiating a portion where a recognition pattern and a circuit pattern are formed on a wafer. Accordingly, the scattered light scattered by the detector is formed to form image data. The image data is processed to confirm recognition codes and to detect defects in circuit patterns. In particular, even when the film is stacked on the part where the recognition code is formed, even if the image of the recognition code is blurred or dark, diffuse reflection occurs at the lower part of the film, so that distinct scattered light can be obtained. Therefore, the recognition rate of the recognition code of the wafer is increased. In addition, since the check result of the recognition code and the circuit pattern are collectively processed and uploaded to the database, an error occurring when uploading data can be minimized.

Description

Method and apparatus for inspecting semiconductor wafers {Method and apparatus for inspecting semiconductor wafer}

TECHNICAL FIELD The present invention relates to a semiconductor wafer inspection method and apparatus, and more particularly, to a semiconductor wafer inspection method and apparatus that irradiates a laser beam onto a semiconductor wafer and thereby uses laser scattering.

In general, a semiconductor device is manufactured by repeating a process of stacking different circuit patterns on a wafer surface one by one using a photolithography process, and as a result, a plurality of circuit patterns are stacked on the wafer. As described above, when the circuit patterns are stacked on the wafer in multiple layers, a process of checking whether the circuit patterns formed in each layer are normally formed or whether defects or abnormalities are generated in the circuit patterns is performed. One is a semiconductor wafer inspection apparatus. The inspection apparatus mainly uses a method of detecting scattered light of a laser beam scanned in a pattern to detect a defect on the pattern.

In addition, as the types of semiconductor devices are diversified, many problems are generated in managing wafers in units of cassettes, and various attempts have recently been made to individually manage wafers. In particular, in order to manage the wafers individually and accurately, the wafer identification code engraved on each wafer must be correctly recognized. Recognition codes are formed on each wafer by photolithography to etch the silicon surface or by imprinting the surface with a laser beam, wherein the flat zone of the semiconductor wafer is selected as the surface.

1, a conventional wafer inspection apparatus is shown. In the conventional wafer inspection apparatus, a device for recognizing a recognition code of a wafer is provided separately.

The conventional wafer inspection apparatus includes a laser beam providing unit 110. The laser beam 120 provided by the laser beam providing unit 110 is scanned while scanning the surface of the wafer W on the stage 100. Scattered light 130 scattered on the surface of the wafer W may be detected by the detector 140 to easily obtain data on defects on the surface of the wafer. On the other hand, in order to recognize the recognition code of the wafer (W), the laser beam providing unit 110 irradiates the laser beam 120 to the recognition code formed on the wafer (W). In this case, the laser beam 120 serves as an illumination. By receiving the reflected light 150 reflected on the wafer W by the light detecting imaging means 160, the recognition code is decoded to identify the wafer W. FIG. The laser beam providing unit 110 according to the above method may be a helium-neon gas laser that sufficiently includes 3.39 μm infrared rays, and a charge-coupled device (CCD) sensor is generally used as the imaging unit 140 for detection. .

However, when the portion where the recognition code is formed on the wafer W is dark or blurred due to the deposition layers on the surface of the wafer W, the recognition code may not be recognized. In addition, since the conventional technology as described above is equipped with a separate recognition code recognition device, the installation cost increases. In addition, the recognition code recognized by the recognition code recognition device and the recognition result of the semiconductor wafer circuit pattern generated separately from the recognition code recognition device are synthesized to form data on the wafer. Therefore, when the recognition code is not confirmed, the recognition code and the circuit pattern test result are not synthesized to form accurate data. In addition, an error may occur when combining the recognition code and the circuit pattern test result. Therefore, a problem arises in the stability and reliability of the data.

In order to solve the above problems, there is provided a wafer inspection method and apparatus capable of inspecting a wafer and confirming a recognition pattern.

1 is a schematic configuration diagram illustrating a conventional wafer inspection apparatus.

2 is a schematic diagram illustrating a semiconductor wafer inspection apparatus according to an embodiment of the present invention.

3 is a schematic plan view illustrating the movement of a wafer between a cassette, a pre-aligner and a chamber in accordance with one embodiment of the present invention.

4 is a flowchart for explaining a semiconductor wafer inspection method using the semiconductor wafer inspection apparatus shown in FIG. 2.

Explanation of symbols on the main parts of the drawings

200: chamber 210: door

220: laser beam supply unit 230: laser beam

240: scattered light 250: XY stage

260 detection unit 270 driving unit

280 control unit 300 data forming unit

310: photoelectric amplifier tube 320: A / D converter

400: data processing unit 500: cassette

600: preliminary aligner 610: edge sensor

620: alignment mark sensor 630, 640: transfer arm

W: Wafer

The present invention to achieve the above object,

Mounting a semiconductor wafer on an XY stage, irradiating and scanning a portion where a recognition pattern is formed on the semiconductor wafer with a laser beam, detecting first scattered light scattered by the laser beam irradiation; Forming first image data of the recognition pattern from the first scattered light, checking the recognition code of the semiconductor wafer by processing the first image data, and forming a portion of the circuit pattern on the semiconductor wafer. Scanning by irradiating with a laser beam, detecting second scattered light scattered by the laser beam irradiation, forming second image data of the circuit pattern from the second scattered light, and the first image data Processing the semiconductor wafer to detect defects in the semiconductor wafer circuit pattern It provides a wiper inspection method.

In addition, the semiconductor wafer inspection method is performed prior to the mounting step of the semiconductor wafer, pre-aligning the semiconductor wafer, and batch processing the data of the recognition code and the inspection result of the circuit pattern to upload to the database It further includes.

The semiconductor wafer inspection apparatus according to the present invention for achieving the above object,

A laser beam providing unit for irradiating a laser beam onto a portion where a recognition pattern and a circuit pattern are formed on a semiconductor wafer, and supporting the semiconductor wafer, wherein the laser beam scans a portion where the recognition pattern and the circuit pattern are formed, respectively An XY stage for moving the semiconductor wafer, a detector for detecting first and second scattered light scattered from portions where the recognition pattern and the circuit pattern are formed, and respective images from the first and second scattered light. And first and second image data forming parts to be formed, and a data processing part to check a recognition code from the first and second image data and to detect a defect in a circuit pattern.

The semiconductor inspection apparatus includes a preliminary aligner for detecting the flat zone and the alignment mark of the semiconductor wafer to align the semiconductor wafer, a driving unit for driving the XY stage so that the semiconductor wafer is scanned by the laser beam; It further includes a control unit for controlling the driving of the drive unit. In addition, the data processing unit performs a function of collectively processing the data of the identification code and the inspection result of the circuit pattern to upload to the database.

Since the semiconductor wafer inspection apparatus uses scattered light detection according to laser beam irradiation, the recognition code of the wafer can be confirmed even if a film is laminated on the wafer and the image of the recognition code is blurred or dark. In addition, since a recognition code recognition device including a detection image pickup means such as a CCD sensor is installed separately, the recognition code is recognized using a semiconductor wafer inspection device, thereby reducing the cost of equipment. The results of the pattern check are processed in batches and uploaded directly to the database. Therefore, it is possible to increase the recognition rate of the wafer recognition code and to eliminate the possibility of error in synthesizing the data, thereby increasing the stability and reliability of the data.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a schematic configuration diagram illustrating a semiconductor wafer inspection apparatus according to an embodiment of the present invention, and FIG. 3 is a schematic plan view illustrating movement of the wafer W between a cassette, a pre-aligner, and a chamber. to be.

2 and 3, the semiconductor wafer W inspection apparatus employs a method using laser scattering. The inspection apparatus is provided with a chamber 200. The chamber 200 provides a space for a process of inspecting a circuit pattern and a process of recognizing a recognition code.

The upper portion of the chamber 200 is provided with a laser beam providing unit 220 for providing a laser beam 230 irradiated to the semiconductor wafer (W). The laser beam providing unit 220 generates a laser and irradiates the generated laser.

A laser is the amplification of light using the induced emission of electromagnetic waves. Looking at the principle, when an electromagnetic wave (or photon) is incident on a stable atom, the atom absorbs the energy of light and is excited. The atoms that absorb the next energy become unstable and release energy within a short time. The release of energy is called a transition. Emissions by transition are roughly divided into spontaneous emission and stimulated emission. When an electromagnetic wave with a frequency υ exists and an electromagnetic wave is incident while the atoms are excited, a transition to a stable state occurs and a photon having an energy of hυ is generated. This is distinguished from natural emission and causes a kind of resonance phenomenon in which the photon's frequency, phase and polarization all emit the same photon. This is called stimulated emission and the emitted electromagnetic wave has a constant phase relationship.

Incident light that causes induced emission acts only by stimulation of excited atoms, so it is not converted or reduced to other energy and increases to two photons including photons generated by induced emission. This is called amplification of light. In order for the light to be amplified, the light is amplified only when a lot of atoms are placed in the excited state. It is called an inversion distribution that places many atoms in this excited state.

Since amplification of the light by induced emission alone does not produce an efficient laser light, a parallel mirror is used to resonate the light. Induced emission occurs while the inverted distribution continues and the beam is amplified when the beam is returned to the laser medium section by the reflecting mirror. Induced emission increases rapidly due to the wave, and this structure is called a light resonator and laser light is emitted.

The laser is classified into a solid laser, a gas laser, a liquid laser, and a semiconductor laser according to the medium used, and is classified into an ultraviolet laser, a visible light laser, and an infrared laser according to the wavelength of light output. In addition, it is divided into optical pumping laser, electric pumping laser and chemical pumping laser according to the kind of energy supplied from the outside. The laser beam 230 emits infrared light having a wavelength range of about 750 to 1000 nanometers (nm), visible light having a wavelength range of about 400 to 750 nanometers, and ultraviolet light having a wavelength range of about 10 to 400 nanometers, respectively. Can be used as a source

The lower portion of the chamber 200 is provided with an XY stage 250 on which the semiconductor wafer (W) is placed. The position of the XY stage 250 is moved in the X-axis and Y-axis direction by the drive unit 270. The driving unit 270 moves the XY stage 250 so that the portion where the recognition code and the circuit pattern of the semiconductor wafer W are formed is scanned by the laser beam 230. The controller 280 is connected to the driver 270 to control the driving of the driver 270 as described above. In some cases, the driving unit 270 may be connected to the laser beam providing unit 220 to drive the laser beam providing unit 220, and the control unit 280 may be connected to the driving unit 280.

One side of the chamber 200 is provided with a door 210 in which the semiconductor wafer W is loaded, and a pre-aligner 600 is provided outside the chamber 200 and one side of the door 210. One side of the preliminary sorter 600 is provided with a cassette 500 in which a plurality of semiconductor wafers W are accommodated. Pre-aligner 600 pre-aligns wafer W before loading wafer W into chamber 200. The preliminary aligner 600 includes an edge sensor 610 and an alignment mark sensor 620. The edge sensor 610 is for detecting the flat zone of the wafer W, and typically includes a light emitting element and a light receiving element. In addition, the alignment mark sensor 620 is for detecting the alignment mark formed in the side of the wafer (W). Since the alignment mark of the wafer W is detected by the alignment mark sensor 620 in the state where the flat zone is primarily detected by the edge sensor 610, more precise preliminary alignment of the wafer W is possible. do.

When the laser beam providing unit 220 is irradiated to the semiconductor wafer W on the side surface of the chamber 200, the laser beam 230 diffusely reflected on the semiconductor wafer W is scattered to detect scattered light 240 generated. Scattered light 240 detector 260 is provided. The laser beam 230 incident on the semiconductor wafer W is scattered while causing diffuse reflection by hitting a portion where a recognition code and a circuit pattern are formed on the wafer W. In particular, a film is stacked on the wafer W on which the recognition code is formed to generate scattered light 240 due to the diffuse reflection even if the image of the recognition code is dark or blurred. The scattered light 240 is detected through the scattered light detector 260.

The image data forming unit 300 forms scattered light 240 detected by the scattered light detector 260 as image data. The image data converter 400 includes a photomultiplayer tube (PMT) 310 and an analog / digital converter 320. The scattering particles amplified by the optoelectronic amplification tube 310 is converted into an electrical signal, and the electrical signal is converted into image data having a digital signal form through the A / D converter 320 to form image data. do.

The data processor 500 confirms the recognition code from the image data and detects a defect of the circuit pattern. In addition, the data processing unit 500 performs a function of collectively processing and uploading the identified recognition code and the inspection result of the circuit pattern to the database. The uploaded data is then utilized in the process.

3 shows the movement of the wafer W between the cassette 500, the preliminary aligner 600, and the chamber 200. First, the wafer W accommodated in the cassette 500 is transferred to the preliminary aligner 600 by the first transfer arm 630. The wafer W pre-aligned in the pre-aligner 600 is loaded into the chamber 200 by the second transfer arm 640. The wafer W, which is loaded into the chamber 200 and has completed the process of recognizing the wafer recognition code and the semiconductor inspection process, is transferred to the preliminary aligner 600 by the second transfer arm 640, and then again the first wafer. It is transferred to and received by the cassette 500 by the transfer arm 630.

Next, a method of confirming the recognition pattern and the circuit pattern formed on the semiconductor wafer W will be described with reference to the flowchart of the semiconductor wafer inspection method using the semiconductor wafer W inspection apparatus shown in FIG. 4.

First, a cassette 500 containing a plurality of semiconductor wafers W is mounted on a stage provided outside the main facility. The wafer W of the cassette 500 is transferred to the preliminary aligner 600 using the first transfer arm 630. Before loading the wafer W into the chamber 200, the wafer W is pre-arranged so that the flat zone is positioned in one direction using the pre-aligner 600 (S100).

Next, the semiconductor wafer W pre-aligned in the preliminary aligner 600 is seated on the XY stage 250 provided in the lower portion of the chamber 200 by using the second transfer arm 640. (S200)

Subsequently, the laser beam 230 provided from the laser beam providing unit 220 is irradiated to the portion where the recognition pattern of the semiconductor wafer W is formed and scanned. (S300) The area of the irradiated laser beam 230 is narrow. Because of this, the site where the recognition pattern is formed cannot be irradiated at one time. Therefore, the driving unit 270 moves the XY stage 250 in the X-axis and Y-axis directions so that the laser beam 230 can sufficiently scan the portion where the recognition pattern is formed. On the other hand, the XY stage is fixed and the laser beam providing unit 220 may be moved to scan the area where the recognition pattern is formed. In addition, the XY stage and the laser beam providing unit may move at the same time to scan the portion where the recognition pattern is formed.

The first scattered light is generated by irradiating the laser beam 230 provided from the laser beam providing unit 220 to a portion where the recognition pattern is formed, and being scattered from the portion where the recognition pattern is formed by the laser beam 230. In operation S400, even when deposition layers are stacked on a portion where the recognition pattern of the wafer W is formed, the laser beam 230 irradiated from the laser beam providing unit 220 passes through the deposition layers and the wafer may be detected. A recognition pattern formed on (W) is reached. The laser beam 230 reached is scattered and scattered in the recognition pattern, thereby detecting the first scattered light 240a.

The detected first scattered light 240a is transmitted to the image data forming unit 300a, and the image data forming unit 300 forms first image data of the recognition pattern from the first scattered light 240 (S500). In this case, the scattering particles amplified by the optoelectronic amplifying tube 310 are converted into an electrical signal, and the electrical signal is converted into image data having a digital signal form through the A / D converter 320.

Subsequently, the first image data is transmitted to the data processing unit 400 to confirm the recognition code of the wafer W. (S600) In order to confirm the recognition code, a program for recognizing the recognition pattern as image data is used. The recognition code can be confirmed.

Next, the laser beam 230 provided from the laser beam providing unit 220 is irradiated to the portion where the circuit pattern of the semiconductor wafer W is formed and scanned. (S700) The portion where the circuit pattern is formed is laser beam 230. The driving unit 270 moves the XY stage 250 in the X-axis and Y-axis directions so that the scanning can be sufficiently performed. On the other hand, the XY stage is fixed and the laser beam providing unit 220 may be moved to scan the portion where the circuit pattern is formed. In addition, the XY stage and the laser beam providing unit may move at the same time to scan the portion where the circuit pattern is formed.

The second scattered light 240b generated by irradiating the laser beam 230 provided from the laser beam providing unit 220 to a portion where the circuit pattern is formed and scattered from the portion where the circuit pattern is formed by the laser beam 230. (S800).

The detected second scattered light 240b is transmitted to the image data forming unit 300, and the image data forming unit 300 forms second image data from the second scattered light 240b. Scattered particles amplified by the optoelectronic amplification tube 310 is converted into an electrical signal, which is in turn converted into image data having a digital signal form through the A / D converter 320.

Subsequently, the second image data is transmitted to the data processor 400 to detect a defect of a circuit pattern of the wafer W. (S1000) In order to detect a defect of the circuit pattern, the second image data and the pre-input are input. Comparative analysis of the reference image data. That is, by comparing the digitized image data, it is determined whether the circuit pattern formed on the semiconductor wafer is defective.

Finally, the inspection result of the recognized identification code and the circuit pattern is uploaded to the database directly from the data processing unit 400 (S1100). You can process data in batch and upload it directly to the database.

The semiconductor wafer inspection apparatus detects scattered light obtained by irradiating a laser beam not only to a portion where a circuit pattern is formed on the wafer but also to a portion where a recognition code is formed, thereby confirming the recognition code of the wafer and detecting a defect in the circuit pattern. As a CCD sensor does not require a separate device for recognizing a recognition code of a wafer, installation cost is reduced. Since a film is laminated on the part where the recognition code is formed, clear scattered light can be obtained even if the image of the recognition code is blurred or dark, and the recognition rate of the recognition code of the wafer is increased. In addition, since the identified recognition code and the circuit pattern check result are collectively processed and uploaded to a database, errors occurring during data upload are minimized. Therefore, the stability and reliability of the data can be improved.

Although the present invention has been described with reference to the preferred embodiments of the present invention as described above, those skilled in the art do not depart from the spirit and scope of the present invention as set forth in the claims below. It will be understood that various modifications and variations can be made.

Claims (8)

Mounting a semiconductor wafer on an XY stage; Irradiating and scanning a portion where the recognition pattern is formed on the semiconductor wafer with a laser beam; Detecting first scattered light scattered by the laser beam irradiation; Forming first image data of the recognition pattern from the first scattered light; Processing the first image data to identify a recognition code of the semiconductor wafer; Irradiating a portion where a circuit pattern is formed on the semiconductor wafer by scanning with a laser beam; Detecting second scattered light scattered by the laser beam irradiation; Forming second image data of the circuit pattern from the second scattered light; And Processing the first image data to detect defects in the semiconductor wafer circuit pattern. The method of claim 1, further comprising pre-aligning the semiconductor wafer, which is performed prior to the step of mounting the semiconductor wafer. The method of claim 1, further comprising uploading a data of the recognition code and the inspection result of the circuit pattern to a database in a batch. A laser beam providing unit for irradiating a laser beam to a portion where a recognition pattern and a circuit pattern are formed on a semiconductor wafer, respectively; An XY stage for supporting the semiconductor wafer and for moving the semiconductor wafer such that the laser beam scans a portion where the recognition pattern and the circuit pattern are formed, respectively; A detector for detecting first and second scattered light scattered from portions where the recognition pattern and the circuit pattern are formed; First and second image data forming units for forming respective images from the first and second scattered light; And And a data processor for checking a recognition code from the first and second image data and detecting a defect in a circuit pattern. The apparatus of claim 4, further comprising a preliminary aligner for detecting the flat zone and the alignment mark of the semiconductor wafer to align the semiconductor wafer. 5. The apparatus of claim 4, further comprising: a driver for driving the XY stage for scanning the semiconductor wafer by the laser beam; And And a control unit for controlling driving of the driving unit. The semiconductor wafer inspection apparatus according to claim 4, wherein the data processing unit further performs a function of collectively processing the data of the recognition code and the inspection result of the circuit pattern and uploading the data to a database. The display apparatus of claim 4, wherein the image data forming unit comprises: an optoelectronic amplifying tube configured to amplify the detected scattered light into an electrical signal; And And an analog / digital converter for converting the electrical signal into the image data in the form of a digital signal.